The present invention relates to methods and apparatus for measuring the weight of an occupying item of a seat, in particular, a seat in an automotive vehicle.
The present invention also relates to apparatus and methods for adjusting a vehicle component, system or subsystem in which the occupancy of a seat, also referred to as the xe2x80x9cseated statexe2x80x9d herein, is evaluated using at least a weight measuring apparatus and the component, system or subsystem may then be adjusted based on the evaluated occupancy thereof. The vehicle component, system or subsystem, hereinafter referred to simply as a component, may be any adjustable component of the vehicle including, but not limited to, the bottom portion and backrest of the seat, the rear view and side mirrors, the brake, clutch and accelerator pedals, the steering wheel, the steering column, a seat armrest, a cup holder, the mounting unit for a cellular telephone or another communications or computing device and the visors. Further, the component may be a system such an as airbag system, the deployment or suppression of which is controlled based on the seated-state of the seat. The component may also be an adjustable portion of a system the operation of which might be advantageously adjusted based on the seated-state of the seat, such as a device for regulating the inflation or deflation of an airbag that is associated with an airbag system.
The present invention also relates to apparatus and method for automatically adjusting a vehicle component to a selected or optimum position for an occupant of a seat based on at least two measured morphological characteristics of the occupant, one of which is the weight of the occupant. Other morphological characteristics include the height of the occupant, the length of the occupant""s arms, the length of the occupant""s legs, the occupant""s head diameter and the inclination of the occupant""s back relative to the seat bottom. Other, unlisted morphological characteristics are also envisioned for use in the invention.
Automobiles equipped with airbags are well known in the prior art. In such airbag systems, the car crash is sensed and the airbags rapidly inflated thereby insuring the safety of an occupation in a car crash. Many lives have now been saved by such airbag systems. However, depending on the seated state of an occupant, there are cases where his or her life cannot be saved even by present airbag systems. For example, when a passenger is seated on the front passenger seat in a position other than a forward facing, normal state, e.g., when the passenger is out of position and near the deployment door of the airbag, there will be cases when the occupant will be seriously injured or even killed by the deployment of the airbag.
Also, sometimes a child seat is placed on the passenger seat in a rear facing position and there are cases where a child sitting in such a seat has been seriously injured or killed by the deployment of the airbag.
Furthermore, in the case of a vacant seat, there is no need to deploy an airbag, and in such a case, deploying the airbag is undesirable due to a high replacement cost and possible release of toxic gases into the passenger compartment. Nevertheless, most airbag systems will deploy the airbag in a vehicle crash even if the seat is unoccupied.
For these reasons, there has been proposed a seated-state detecting unit such as disclosed in the following U.S. patents, which are incorporated herein by reference in their entirety to the extent the disclosure of these patents is necessary, assigned to the current assignee of the present application: Breed et al. U.S. Pat. No. 5,563,462); Breed et al. (U.S. Pat. No. 5,829,782); Breed et al. (U.S. Pat. No. 5,822,707): Breed et al. (U.S. Pat. No. 5,694,320); Breed et al. (U.S. Pat. No. 5,748,473); and Varga et al. (U.S. Pat. No. 5,943,295). Typically, in some of these designs three or four sensors or sets of sensors are installed at three or four points in a vehicle passenger compartment for transmitting ultrasonic or electromagnetic waves toward the passenger or driver""s seat and receiving the reflected waves. Using appropriate hardware and software, the approximate configuration of the occupancy of either the passenger or driver seat can be determined thereby identifying and categorizing the occupancy of the relevant seat.
However, in the aforementioned literature using ultrasonics, the pattern of reflected ultrasonic waves from an adult occupant who may be out of position is sometimes similar to the pattern of reflected waves from a rear facing child seat. Also, it is sometimes difficult to discriminate the wave pattern of a normally seated child with the seat in a rear facing position from an empty seat with the seat in a more forward position. In other cases, the reflected wave pattern from a thin slouching adult with raised knees can be similar to that from a rear facing child seat. In still other cases, the reflected pattern from a passenger seat which is in a forward position can be similar to the reflected wave pattern from a seat containing a forward facing child seat or a child sitting on the passenger seat. In each of these cases, the prior art ultrasonic systems can suppress the deployment of an airbag when deployment is desired or, alternately, can enable deployment when deployment is not desired.
If the discrimination between these cases can be improved, then the reliability of the seated-state detecting unit can be improved and more people saved from death or serious injury. In addition, the unnecessary deployment of an airbag can be prevented.
With respect to the adjustment of a vehicular seat, the adjustment of an automobile seat occupied by a driver of the vehicle is now accomplished by the use of either electrical switches and motors or by mechanical levers. As a result, the driver""s seat is rarely placed at the proper driving position which is defined as the seat location which places the eyes of the driver in the so-called xe2x80x9ceye ellipsexe2x80x9d and permits him or her to comfortably reach the pedals and steering wheel. The xe2x80x9ceye ellipsexe2x80x9d is the optimum eye position relative to the windshield and rear view mirror of the vehicle.
The eye ellipse, which is actually an ellipsoid, is rarely achieved by the actions of the driver for a variety of reasons. One specific reason is the poor design of most seat adjustment systems particularly the so-called xe2x80x9c4-way-seatxe2x80x9d. It is known that there are three degrees of freedom of a seat bottom, namely vertical, longitudinal, and rotation about the lateral or pitch axis. The 4-way-seat provides four motions to control the seat: (1) raising or lowering the front of the seat, (2) raising or lowering the back of the seat, (3) raising or lowering the entire seat, (4) moving the seat fore and aft. Such a seat adjustment system causes confusion since there are four control motions for three degrees of freedom. As a result, vehicle occupants are easily frustrated by such events as when the control to raise the seat is exercised, the seat not only is raised but is also rotated. Occupants thus find it difficult to place the seat in the optimum location using this system and frequently give up trying leaving the seat in an improper driving position
Many vehicles today are equipped with a lumbar support system that is never used by most occupants. One reason is that the lumbar support cannot be preset since the shape of the lumbar for different occupants differs significantly, i.e., a tall person has significantly different lumbar support requirements than a short person. Without knowledge of the size of the occupant, the lumbar support cannot be automatically adjusted.
As discussed in the above referenced ""320 patent, in approximately 95% of the cases where an occupant suffers a whiplash injury, the headrest is not properly located to protect him or her in a rear impact collision. Also, the stiffness and damping characteristics of a seat are fixed and no attempt is made in any production vehicle to adjust the stiffness and damping of the seat in relation to either the size or weight of an occupant, or to the environmental conditions such as road roughness. All of these adjustments, if they are to be done automatically, require knowledge of the morphology of the seat occupant.
Systems are now being used to attempt to identify the vehicle occupant based on a coded key or other object carried by the occupant. This requires special sensors within the vehicle to recognize the coded object. Also, the system only works if the coded object is used by the particular person for whom the vehicle was programmed. If the vehicle is used by a son or daughter, for example, who use their mother""s key then the wrong seat adjustments are made. Also, these systems preserve the choice of seat position without any regard for the correctness of the seat position. With the problems associated with the 4-way seats, it is unlikely that the occupant ever properly adjusts the seat. Therefore, the error will be repeated every time the occupant uses the vehicle.
Moreover, these coded systems are a crude attempt to identify the occupant. An improvement can be made if the morphological characteristics of the occupant can be measured as described below. Such measurements can be made of the height and weight, for example, and used not only to adjust a vehicular component to a proper position but also to remember that position, as fine tuned by the occupant, for re-positioning the component the next time the occupant occupies the seat. For the purposes herein, a morphological characteristic will mean any measurable property of a human such as height, weight, leg or arm length, head diameter etc.
As discussed more fully below, in a preferred implementation, once at least one and preferably two of the morphological characteristics of a driver are determined, e.g., by measuring his or her height and weight, the component such as the seat can be adjusted and other features or components can be incorporated into the system including, for example, the automatic adjustment of the rear view and/or side mirrors based on seat position and occupant height. In addition, a determination of an out-of-position occupant can be made and based thereon, airbag deployment suppressed if the occupant is more likely to be injured by the airbag than by the accident without the protection of the airbag. Furthermore, the characteristics of the airbag including the amount of gas produced by the inflator and the size of the airbag exit orifices can be adjusted to provide better protection for small lightweight occupants as well as large, heavy people. Even the direction of the airbag deployment can, in some cases, be controlled.
Still other features or components can now be adjusted based on the measured occupant morphology as well as the fact that the occupant can now be identified. Some of these features or components include the adjustment of seat armrest, cup holder, steering wheel (angle and telescoping), pedals, phone location and for that matter the adjustment of all things in the vehicle which a person must reach or interact with. Some items that depend on personal preferences can also be automatically adjusted including the radio station, temperature, ride and others.
Heretofore, various methods have been proposed for measuring the weight of an occupying item of a vehicular seat. The methods include pads, sheets or films that have placed in the seat cushion which attempt to measure the pressure distribution of the occupying item. Prior to its first disclosure in U.S. Pat. No.5,822,707 referenced above, systems for measuring occupant weight based on the strain in the seat structure had not been considered. Prior art weight measurement systems have been notoriously inaccurate. Thus, a more accurate weight measuring system is desirable. The strain measurement systems described herein, substantially eliminate the inaccuracy problems of prior art systems and permit an accurate determination of the weight of the occupying item of the vehicle seat. Additionally, as disclosed herein, in many cases, sufficient information can be obtained for the control of a vehicle component without the necessity of determining the entire weight of the occupant. For example, the force that the occupant exerts on one of the three support members may be sufficient.
Most, if not all, of the problems discussed above are difficult to solve or unsolvable using conventional technology.
Accordingly, it is a principal object of the present invention to provide new and improved apparatus and methods for measuring the weight of an occupying item on a vehicle seat which apparatus and methods may be integrated into vehicular component adjustment apparatus and methods which evaluate the occupancy of the seat and adjust the location and/or orientation relative to the occupant and/or operation of a part of the component or the component in its entirety based on the evaluated occupancy of the seat.
It is another object of the present invention to provide new and improved vehicular seats including a weight measuring feature and weight measuring methods for implementation in connection with vehicular seats.
It is yet another object of the present invention to provide new and improved vehicular seats in which the weight applied by an occupying item to the seat is measured based on capacitance between conductive and/or metallic members underlying the seat cushion.
It is another object of the present invention to provide new and improved adjustment apparatus and methods that evaluate the occupancy of the seat and adjust the location and/or orientation relative to the occupant and/or operation of a part of the component or the component in its entirety based on the evaluated occupancy of the seat and on a measurement of the occupant""s weight or a measurement of a force exerted by the occupant on the seat.
It is another object of the present invention to provide new and improved adjustment apparatus and methods that evaluate the occupancy of the seat by a combination of ultrasonic sensors and additional sensors and adjust the location and/or orientation relative to the occupant and/or operation of a part of the component or the component in its entirety based on the evaluated occupancy of the seat.
It is another object of the present invention to provide new and improved adjustment apparatus and methods that reliably discriminate between a normally seated passenger and a forward facing child seat, between an abnormally seated passenger and a rear facing child seat, and whether or not the seat is empty and adjust the location and/or orientation relative to the occupant and/or operation of a part of the component or the component in its entirety based thereon.
It is another object of the present invention to provide an improved weight measurement system and thereby improve the accuracy of another apparatus or system which utilizes measured weight as input, e.g., a component adjustment apparatus.
It is another object of the present invention to provide new and improved adjustment apparatus and methods that evaluate the occupancy of the seat without the problems mentioned above.
Additional objects and advantages of this invention include:
1. To provide a system for passively and automatically adjusting the position of a vehicle component to a near optimum location based on the size of an occupant.
2. To provide a system for recognizing a particular occupant of a vehicle and thereafter adjusting various components of the vehicle in accordance with the preferences of the recognized occupant.
3. To provide systems for approximately locating the eyes of a vehicle driver to thereby permit the placement of the driver""s eyes at a particular location in the vehicle.
4. To provide a pattern recognition system to permit more accurate location of an occupant""s head and the parts thereof and to use this information to adjust a vehicle component.
5. To provide a method of determining whether a seat is occupied and, if not, leaving the seat at a neutral position.
6. To provide a system for automatically adjusting the position of various components of the vehicle to permit safer and more effective operation of the vehicle including the location of the pedals and steering wheel.
7. To determine whether an occupant is out-of-position relative to the airbag and if so, to suppress deployment of the airbag in a situation in which the airbag would otherwise be deployed.
8. To adjust the flow of gas into and/or out of the airbag based on the morphology and position of the occupant to improve the performance of the airbag in reducing occupant injury.
9. To provide a system where the morphological characteristics of an occupant are measured by sensors located within the seat.
10. To provide a system and method wherein the weight of an occupant is determined utilizing sensors located on the seat structure.
Further objects of the present invention will become apparent from the following discussion of the preferred embodiments of the invention.
Accordingly, in order to achieve one or more of the objects above, a vehicle seat structure comprises a seat defining a surface adapted to contact an occupying item and a weight sensor arrangement arranged in connection with the seat for providing an indication of the weight applied by the occupying item to the surface of the seat. The weight sensor arrangement includes conductive members spaced apart from one another such that a capacitance develops between opposed ones of the conductive members upon incorporation of the conductive members in an electrical circuit. The capacitance is based on the space between the conductive members which varies in relation to the weight applied by the occupying item to the surface of the seat. The weight sensor arrangement may include a pair of non-metallic substrates and a layer of material situated between the non-metallic substrates, possibly a compressible material. The conductive members may comprise a first electrode arranged on a first side of the material layer and a second electrode arranged on a second side of the material layer. The weight sensor arrangement may be arranged in connection with slide mechanisms adapted to support the seat on a substrate of the vehicle while enabling movement of the seat, possibly between the slide mechanisms and the seat. If bolts attach the seat to the slide mechanisms, the conductive members may be annular and placed on the bolts.
Another embodiment of a seat structure comprises a seat defining a surface adapted to contact an occupying item, slide mechanisms adapted to support the seat on a substrate of the vehicle while enabling movement of the seat and a weight sensor arrangement interposed between the seat and the slide mechanisms for measuring displacement of the seat which provides an indication of the weight applied by the occupying item to the seat. The weight sensor arrangement can include a capacitance sensor which measures a capacitance which varies in relation to the displacement of the seat. The capacitance sensor can include conductive members spaced apart from one another such that a capacitance develops between opposed ones of the conductive members upon incorporation of the members in an electrical circuit, the capacitance being based on the space between the members which varies in relation to the weight applied by the occupying item to the seat.
The weight sensor arrangement can comprise a spring system arranged underneath a seat cushion and a sensor arranged in association with the spring system for generating a signal based on downward movement of the cushion caused by occupancy of the seat which is indicative of the weight of the occupying item. The sensor may be a displacement sensor structured and arranged to measure displacement of the spring system caused by occupancy of the seat. Such a sensor can comprise a spring retained at both ends and which is tensioned upon downward movement of the spring system and measuring means for measuring a force in the spring indicative of weight of the occupying item. The measuring means can comprise a strain gage for measuring strain of the spring or a force-measuring device.
The sensor may also comprise a support, a cable retained at one end by the support and a length-measuring device arranged at an opposite end of the cable for measuring elongation of the cable indicative of weight of the occupying item. The sensor can also comprises one or more SAW strain gages and/or structured and arranged to measure a physical state of the spring system.